/**
 * Copyright (C) 2015 The Gravitee team (http://gravitee.io)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package io.gravitee.gateway.handlers.api.processor.cors;

import io.gravitee.common.http.HttpHeaders;
import io.gravitee.common.http.HttpStatusCode;
import io.gravitee.gateway.api.ExecutionContext;
import io.gravitee.gateway.api.Invoker;
import io.gravitee.gateway.api.buffer.Buffer;
import io.gravitee.gateway.api.handler.Handler;
import io.gravitee.gateway.api.proxy.ProxyConnection;
import io.gravitee.gateway.api.proxy.ProxyResponse;
import io.gravitee.gateway.api.stream.ReadStream;
import io.gravitee.gateway.api.stream.WriteStream;

/**
 * This specific preflight request {@link Invoker} is ran if the gateway has to process policies once preflight
 * processing has been done. This allows to run specific policies even if no upstream is invoked.
 *
 * @author David BRASSELY (david.brassely at graviteesource.com)
 * @author GraviteeSource Team
 */
public class CorsPreflightInvoker implements Invoker {

    @Override
    public void invoke(ExecutionContext context, ReadStream<Buffer> stream, Handler<ProxyConnection> connectionHandler) {
        CorsPreflightProxyConnection connection = new CorsPreflightProxyConnection();
        connectionHandler.handle(connection);
        connection.end();
    }

    private static class CorsPreflightProxyConnection implements ProxyConnection {

        private Handler<ProxyResponse> responseHandler;

        @Override
        public WriteStream<Buffer> write(Buffer content) {
            return this;
        }

        @Override
        public void end() {
            responseHandler.handle(new CorsPreflightProxyResponse());
        }

        @Override
        public ProxyConnection responseHandler(Handler<ProxyResponse> responseHandler) {
            this.responseHandler = responseHandler;
            return this;
        }
    }

    private static class CorsPreflightProxyResponse implements ProxyResponse {

        private final HttpHeaders headers = new HttpHeaders();
        private Handler<Void> endHandler;

        @Override
        public int status() {
            return HttpStatusCode.OK_200;
        }

        @Override
        public HttpHeaders headers() {
            return headers;
        }

        @Override
        public ReadStream<Buffer> bodyHandler(Handler<Buffer> bodyHandler) {
            return this;
        }

        @Override
        public ReadStream<Buffer> endHandler(Handler<Void> endHandler) {
            this.endHandler = endHandler;
            return this;
        }

        @Override
        public ReadStream<Buffer> resume() {
            endHandler.handle(null);
            return this;
        }
    }
}
